Correct the dataType of the modifiers key settings.

chrome/browser/resources/options/chromeos_language_customize_modifier_keys_overlay.html

Index: chrome/browser/resources/options/chromeos_language_customize_modifier_keys_overlay.html
diff --git a/chrome/browser/resources/options/chromeos_language_customize_modifier_keys_overlay.html b/chrome/browser/resources/options/chromeos_language_customize_modifier_keys_overlay.html
index fbecd137cd126a0324e254217e8efb78a5402296..0d6064bd83eb300ef3f39152ea009c4b5614d88d 100644
--- a/chrome/browser/resources/options/chromeos_language_customize_modifier_keys_overlay.html
+++ b/chrome/browser/resources/options/chromeos_language_customize_modifier_keys_overlay.html
@@ -6,7 +6,7 @@
          <td class="option-value">
            <select id="xkb-remap-search-key-to" class="control"
                 pref="settings.language.xkb_remap_search_key_to"
-                dataType="string"
+                dataType="number"
                 i18n-options="xkbRemapSearchKeyToValue"></select>
          </td>
        </tr>
@@ -16,7 +16,7 @@
          <td class="option-value">
            <select id="xkb-remap-control-key-to" class="control"
                 pref="settings.language.xkb_remap_control_key_to"
-                dataType="string"
+                dataType="number"
                 i18n-options="xkbRemapControlKeyToValue"></select>
          </td>
        </tr>
@@ -25,7 +25,7 @@
          <td class="option-value">
            <select id="xkb-remap-alt-key-to" class="control"
                 pref="settings.language.xkb_remap_alt_key_to"
-                dataType="string"
+                dataType="number"
                 i18n-options="xkbRemapAltKeyToValue"></select>
          </td>
        </tr>